1. Field of the Invention
The present invention relates to an exposure technique among lithography techniques for use in a process for a manufacturing method of a semiconductor device, and particularly to a manufacturing method of a semiconductor device with using a so-called liquid immersion exposure method for carrying out an exposure process while a liquid is interposed between a projection optical system of an exposure apparatus and a target substrate applied with exposure processing.
2. Description of the Related Art
Recently, attention has been focused on an exposure method referred to as a liquid immersion exposure method. This liquid immersion exposure method is provided as an exposure method for exposing a pattern on a surface of a resist film while a liquid (immersion liquid) is filled between a projection optical system (projection lens) of an exposure apparatus and a resist film or cover film on a resist film formed on an exposure target substrate applied with exposure processing. An exposure apparatus for use in this liquid immersion exposure method is referred to as a liquid immersion type exposure apparatus. One example of this liquid immersion type exposure apparatus is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-303114.
In Jpn. Pat. Appln. KOKAI Publication No. 10-303114, there is specifically disclosed a liquid immersion type exposure apparatus for carrying out exposure while a stage is relatively moved with respect to the exposure apparatus in a state in which the whole exposure target substrate is immersed in water in a stage capable of supplying water that is an immersion liquid. In the liquid immersion exposure apparatus of such a type, there is a problem that liquid is supplied to the whole stage, and thus, an immersion liquid is prone to overflow from the stage when the stage is moved at a high speed. Therefore, the stage cannot be moved at a high speed.
As a countermeasure against problem of the liquid due to such a stage movement, a technique of moving a stage while an immersion liquid is locally supplied to a portion on an exposure target substrate at which exposure is carried out is disclosed in Soichi Owa and Hiroyuki Nagasaka, Immersion Lithography; its potential performance and issues, Proc. of SPIE Vol. 5040, pp. 724-733. According to this technique, when a stage is moved at a high speed, there is almost no risk that an immersion liquid overflows from the stage, thus enabling high-speed movement of the stage. However, in the case of using such a technique, it is necessary to provide a hydrophobic surface of a resist film, for example, in order to move a liquid film for liquid immersion exposure locally interposed on the surface of the resist film at a high speed. Alternatively, it is necessary to provide another hydrophobic film on the surface of the resist film. These processes with hydrophobic materials enable high-speed relative movement of a stage with respect to an optical system of the exposure apparatus. Finally, throughput improvement of the exposure process can be promoted.
In addition, in another liquid immersion exposure process, a movement speed of a stage in a process for moving a mere exposure target substrate that does not affect an image quality of a pattern exposed on a resist film is made higher than a movement speed of a stage in a liquid immersion movement process that affects an image quality of a pattern. That is, the movement speed of the movement process for moving a stage without exposing a pattern to a resist film is made higher than a movement speed in the liquid immersion exposure process for moving a stage while exposing a pattern onto the resist film. In this manner, throughput improvement of the exposure process can be promoted. At this time, in the movement process for moving a pattern to a resist film without exposure, of course, it is desirable to move the stage at the highest speed.
However, if the stage is simply moved at a high speed, liquid droplets of an immersion liquid are prone to remain on an exposure target substrate along a relative movement trajectory of a projection optical system and the immersion liquid of the exposure apparatus with respect to the exposure target substrate. If the liquid droplets of the immersion liquid remain on the exposure target substrate, a resist pattern formed on a resist film has defects. Consequently, in a semiconductor device manufactured based on a resist pattern having such a defect, there is a high risk that its performance, quality, reliability and the like are lowered.